2.MD.B.6 - About the Math, Learning Targets, and Increasing Rigor

Grade 2 Measurement and Data

2.MD.B.6

Full Standard

Represent whole numbers as lengths from 0 on a number line diagram with equally spaced points corresponding to the numbers 0, 1, 2, ..., and represent whole-number sums and differences within 100 on a number line diagram.

 

Measurement Topic

This standard is reported on the report card in these quarters as follows:

2nd Grade Students Learning 2nd Grade Standards
Quarter 1 Quarter 2 Quarter 3 Quarter 4

Report Card Measurement Topic: Demonstrates understanding of number concepts and relationships

 
1st Grade Students Learning 2nd Grade Standards
Quarter 1 Quarter 2 Quarter 3 Quarter 4

Report Card Measurement Topic: Demonstrates understanding of number concepts and relationships

 

 

About the Math

MeasureSkills and concepts below are learning goals for this standard.

A number line is a useful tool for adding and subtracting whole numbers and fractions. A ruler is a tool built around this concept. This standard should be integrated with computational standards in grade 2. Students should have experiences with an equally partitioned number line before transitioning to an empty (or open) number line.

  • Create a number line with whole number intervals (equal spacing).

Students should have experiences with an equally partitioned number line before transitioning to an empty (or open) number line.

  • Represent whole numbers on a number line.

Students should be able to identify and place numbers on a number line with given endpoints. At first, those endpoints should be static, common endpoints such as 0 and 100, 0 and 1,000, or 0 and 50. In time, students should begin to work with number lines using varied endpoints.

  • Represent a whole number on two different number lines that have different endpoints (e.g. place 80 on a number line that has endpoints of 0 and 100 and 50 and 100).

As students develop an understanding of larger numbers on number lines, we should begin to modify the number lines. Essentially, students need to understand that a number line shows the relationship between numbers. Number lines can have any endpoints. Students should understand that the position of a number changes as the endpoints change. For example, 50 is halfway between 0 and 100 but shifts considerably to the left when those endpoints change to 0 and 1,000 and 50 isn't on a number line with the endpoints of 75 and 90.

  • Find sums and differences within 100 using a number line.

A number line can be used to add and subtract. Students should first add and subtract with a ticked number line before seeing the relationships between ticked and open number lines. In time, students can then work with open number lines. Also, note that students should be able to add and subtract on a number line with varied endpoints. For example, when solving 43 + 35 students shouldn't have to jump from 0 to 43 before adding on 35. Instead, they should be able to start with 43 on the left endpoint.

Essential vocabulary for this standard includes length, unit, number line, sums, differences, measure, and distance

  

Progression of Standard within Grade 2

This progression informs how to develop the standard within the grade level. This progression is provided by HCPSS Elementary Mathematics.

Progression Throughout Year
Quarter 1 Quarter 2 Quarter 3 Quarter 4
  • Create a number line with whole number intervals (equal spacing).
  • Represent whole numbers on a number line.
  • Represent a whole number on two different number lines that have different endpoints (e.g. place 80 on a number line that has endpoints of 0 and 100 and 50 and 100).
  • Find sums and differences within 100 using a number line.

 

 

 

 

Progression of this Standard Across Grades

This progression is informed by the Achieve the Core Coherence Map Links to an external site.. Information is not the complete standard.

Progression Across Grades
Grade  Grade 3

This concept is not taught prior to grade 2.

Understand a fraction as a number on the number line (3.NF.2)

 

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